Gas-fired furnace and intake manifold for low NOx applications

Abstract

A gas-fired air conditioning furnace comprises a monolithic intake manifold including an inlet at a first end and a plurality of outlets at a second end opposite the first end. In addition, the furnace comprises a burner assembly including a plurality of burners, each burner is configured to combust an air-fuel mixture at least partially within an interior space of the burner. Further, each burner extends into one of the outlets of the intake manifold.

What is claimed is: 
     
       1. A gas-fired air conditioning furnace, comprising:
 a monolithic intake manifold including an inlet at a first end and a plurality of outlets at a second end opposite the first end; 
 a burner assembly including a plurality of burners, each burner configured to combust an air-fuel mixture at least partially within an interior space of the burner; and 
 wherein each burner extends into one of the outlets of the intake manifold. 
 
     
     
       2. The furnace of  claim 1 , wherein the intake manifold includes a distributor extending from the first end and a plurality of supply tubes extending from the second end to the distributor;
 wherein the distributor includes the inlet and each supply tube includes one of the plurality of outlets; 
 wherein the distributor is configured to divide the air-fuel mixture among the plurality of supply tubes. 
 
     
     
       3. The furnace of  claim 2 , wherein the distributor includes a plurality of outlets, wherein each of the plurality of outlets of the distributor is configured to supply a portion of the air-fuel mixture to one of the supply tubes. 
     
     
       4. The furnace of  claim 2 , wherein the inlet of the intake manifold has a central axis and each of the supply tubes has a central axis that is parallel to the central axis of the inlet. 
     
     
       5. The furnace of  claim 4 , wherein the central axis of the inlet and the central axis of each supply tube is disposed in a common plane. 
     
     
       6. The furnace of  claim 2 , wherein each burner comprises a cylindrical body having an occluded end disposed in the intake manifold and an open end extending from one of the outlets of the intake manifold. 
     
     
       7. The furnace of  claim 6 , wherein the cylindrical body and the occluded end of each burner includes a plurality of perforations that allow the air-fuel mixture to pass through the cylindrical body and the occluded end into the interior space of the burner. 
     
     
       8. The furnace of  claim 2 , further comprising:
 a post combustion chamber and a plurality of heat exchangers extending from the post combustion chamber, wherein the burner assembly is positioned between the intake manifold and the post combustion chamber, and wherein the heat exchangers are configured to receive hot flue gases from the burners; 
 a mixing tube coupled to the first end of the intake manifold and a gas supply valve coupled to the mixing tube, wherein the mixing tube is adapted to mix air and a fuel supplied by the gas supply valve to form the air-fuel mixture. 
 
     
     
       9. The furnace of  claim 1 , wherein the intake manifold includes a flange positioned between the first end and the second end, wherein the flange couples the intake manifold to a partition panel. 
     
     
       10. An intake manifold for a gas-fired device, comprising:
 a monolithic body having a first end and a second end opposite the first end; 
 an inlet at the first end of the body, the inlet comprising a first axis; 
 a plurality of outlets at the second end of the body; and 
 a mounting flange (1) disposed between the first end of the body and the second end of the body and (2) axially offset along the first axis from each of the first end of the body and the second end of the body; 
 wherein the body includes:
 a distributor section including the inlet and a plurality of supply tubes extending from the distributor section, wherein each supply tube includes one of the plurality of outlets; 
 wherein the distributor is configured to receive an air-fuel mixture through the inlet and divide the air-fuel mixture among the plurality of supply tubes. 
 
 
     
     
       11. The intake manifold of  claim 10 , wherein the distributor section includes a plurality of outlets configured to supply a portion of the air-fuel mixture to the supply tubes. 
     
     
       12. The intake manifold of  claim 11 , wherein each supply tube includes a flow path extending from one of the outlets of the distributor section to one of the outlets of the body. 
     
     
       13. The intake manifold of  claim 12 , wherein the flow path of each supply tube has a central axis that is parallel to the first axis of the inlet. 
     
     
       14. The intake manifold of  claim 13 , wherein the first axis of the inlet and the central axis of each flow path lies in a common plane. 
     
     
       15. A method of operating a gas-fired furnace, comprising:
 (a) supplying an air-fuel mixture to a single-piece intake manifold, wherein the intake manifold has an inlet at a first end and a plurality of outlets at a second end opposite the first end, and wherein the intake manifold includes a distributor extending from the first end and a plurality of supply tubes extending from the second end to the distributor; 
 (b) flowing the air-fuel mixture through the inlet of the intake manifold into the distributor; 
 (c) dividing the air-fuel mixture in the distributor into a plurality of portions; 
 (d) flowing each portion of the air-fuel mixture through one of the supply tubes to a burner extending into the supply tube, wherein one burner extends into each supply tube; 
 (e) combusting the portion of the air-fuel mixture within each burner to form a hot flue gas. 
 
     
     
       16. The method of  claim 15 , further comprising (f) flowing the hot flue gas through each outlet to a heat exchanger. 
     
     
       17. The method of  claim 15 , wherein (d) further comprises flowing each portion of the air fuel mixture through perforations in the corresponding burner. 
     
     
       18. The method of  claim 16 , further comprising (g) flowing air across an exterior surface of each heat exchanger. 
     
     
       19. The method of  claim 18 , further comprising:
 mixing a gaseous fuel and air in a mixing tube to form the air-fuel mixture supplied to the intake manifold.